What do we know about Apple’s new A6 processor?

Apple hasn't said much about its new chip, so we make some educated guesses.

Apple's A5 processor has had some long legs. Originally introduced in the iPad 2 in early 2011, the chip has since proliferated across Apple's entire lineup—versions of it have been included in the iPhone 4S, the Apple TV, and the fifth generation iPod touch. Even the A5X in the 2012 iPad simply pumps up the A5's graphics capabilities while leaving the actual Cortex A9 cores untouched. Between the new iPod touches and the $99 iPhone 4S, it looks like the A5 is going to be for sale well into 2013 and beyond.

If the A5 is any indication, then, we'll be spending the next few years with the A6 chip that Apple introduced in the iPhone 5 yesterday. While the A5 is a thoroughly known quantity at this point, Apple's tendency to avoid talking about specifications means that we know next to nothing about what makes it tick. All we have now are three vague promises: compared to the A5 in the iPhone 4S, the new A6 promises "up to" two times the CPU and graphics performance; the A6 is 22 percent smaller than the A5; and the battery life of the new iPhone is slightly better than the battery life of the 4S. Absent any actual technical data about the new SoC, we're left to do the math ourselves.

Size and battery life

The cause of the reduced size and increased battery life of the iPhone 5 is pretty easy to guess: while the A5 chip in the iPhone 4S is still manufactured on the A5's original 45nm process, the A6 is probably manufactured on Samsung's 32nm process—Apple has already used this process on the A5 in the revised iPad 2 and the most recent Apple TV (and, in all likelihood, the newest iPod touch). Using the new process on an existing design would help Apple and Samsung to work out any kinks, clearing the way toward making a new chip on the same process. Intel's "tick-tock" processor release cadence uses the same methodology to reduce yield issues and other problems that can come from trying to make a new chip on a new process at the same time.

The 32nm Apple A5 is 41 percent smaller than the 45nm version in the iPhone 4S, so a 32nm Apple A6 would have some room to grow while still remaining smaller.

According to Chipworks, the 32nm A5 is about 41 percent smaller than the 45nm version, so a 32nm A6 would have room to add more silicon while still remaining smaller in absolute size. The 32nm A5 in the revised iPad 2 also delivers a 20 to 30 percent battery life increase over the original version with the 45nm chip, so the ten-or-so percent increase in battery life for the iPhone 5 is also pretty plausible, even given the higher-performing SoC.

Increased performance

With all of that in mind, let's look at these doubled performance claims. To get this big of a jump, you can either (1) double the hardware, going from the dual-core CPU and GPU in the A5 to quad-core parts in the A6, or (2) use newer, more efficient architectures, possibly combined with higher clock speeds (increasing clock speeds enough to get twice the performance from the same architecture would probably be too onerous from a power consumption perspective).

So, does the A6 use a quad-core Cortex A9-based chip combined with a quad core GPU? Let's look at the 2012 iPad's A5X, which uses a quad-core GPU to double the A5's graphics power and drive the 2048x1536 Retina Display. Our pals at Chipworks put the die size of the 45nm A5X at 12.90mm by 12.79mm (or 165mm, total), while the 45nm A5 is just 10.09mm by 12.15mm (or 122.6mm, total). Let's assume that if Apple decided to shrink the A5X using Samsung's 32nm process, that the die size would shrink by the same 41 percent, putting the size of a theoretical 32nm A5X at about 97.35mm, or about 21 percent smaller than the 45nm A5.

Enlarge/ The quad-core GPU in Apple's A5X would make it a big chip, even at 32nm.

Now, keep in mind that while Apple says the A5X doubles the graphics performance of the A5, its CPU performance is identical to the older chip. Our 32nm A5X is about the right size and it has the right graphics performance, but it doesn't increase the CPU performance the requisite amount. Thus, it's fair to say that the A6 isn't using a quad-core CPU and GPU to achieve the stated gains.

There's also another reason to go with a faster dual-core CPU than a slower quad-core design: iOS and its apps have been running on the dual-core A5 for some time and as such are already optimized for two cores, and adding another two cores would only unlock those performance gains for developers who put in the extra work.

For these reasons, I think the current scuttlebutt is correct: the A6 is going to be the first chip to market based on the Cortex A15 processor architecture, which is said to be 40 percent faster than older Cortex A9 chips at equal clock speeds. That, combined with higher clock speeds (the A5 in the iPhone 4S is clocked at just 800MHz), could easily get us twice the CPU performance while still using a dual-core design. Even if the two cores are larger than two Cortex A9 cores, they're still not as big as four Cortex A9 cores.

The same holds true for the GPU side: by our calculations, there's probably not enough room for the A5X's quad-core Imagination Technologies SGX543MP4 along with the A15 cores, given what we know about the size of the A6, but a dual-core, faster-clocked Series 6 GPU from Imagination Technologies could likely achieve the same performance while using less space than four less-powerful cores.

Many things have to be true for these assumptions to work out: if Apple is using a 28nm process instead of a 32nm process, or if the A6 is using the same 512MB of RAM as the A5, either of those factors would probably be enough to throw off our math. But given that this is a major chip revision for Apple and that it will probably be serving in not just the next iPad, but future iterations of the Apple TV and iPod touch for the next few years, the use of forward-looking technology makes more sense than would beefing up old technology with more cores or higher clock speeds.

When we know more about the A6 for sure, you can be sure that we'll take a closer look at the chip and its implications for the rest of the market and for current and future Apple devices. For now, this represents our best guess.

Promoted Comments

Interesting analysis. One quibble, though. The RAM on these things is typically a separate die which is then combined with the CPU/GPU die during packaging, so the space required for 512 MB vs 1 GB shouldn't enter into the equation.

Interesting analysis. One quibble, though. The RAM on these things is typically a separate die which is then combined with the CPU/GPU die during packaging, so the space required for 512 MB vs 1 GB shouldn't enter into the equation.

I don't think there's any question that the A6 is running A15 cores, probably two of them. As Qualcomm has demonstrated with Krait, 2 next-gen cores can perform comparably to quad A9s while using less power. It also gives Apple a nice upgrade path to quad core when they do a die shrink next year. The graphics side is more nebulous but the article's analysis is mostly solid.

Apple isn´t shy about talking specs like the OP says. It is just vague and misleading. 2x this and 6x another but when it comes down to it the iPhone probably doesn´t match last generation Android phones.

Apple isn´t shy about talking specs like the OP says. It is just vague and misleading. 2x this and 6x another but when it comes down to it the iPhone probably doesn´t match last generation Android phones.

Except in real-world performance when the iPhone comes across pretty well.

maybe is like comparing apples to oranges (pun not intended), but how does the A5X perform compared to the new A6?

I believe they gave the same vague "2x faster graphics" claim when they introduced the A5X, so I would assume the A6 and A5X would be similar graphically but that the A6 would win out in the CPU department. Like others have said, though, we won't know for sure until we've got hardware in-hand.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz officially and even higher so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

With all of that in mind, let's look at these doubled performance claims. To get this big of a jump, you can either (1) double the hardware, going from the dual-core CPU and GPU in the A5 to quad-core parts in the A6, or (2) use newer, more efficient architectures, possibly combined with higher clock speeds (increasing clock speeds enough to get twice the performance from the same architecture would probably be too onerous from a power consumption perspective).

1.6Ghz is actually right about where a lot of Android A9 devices are shipping, so I don't see why you discount that.

An A15 doesn't quite fit, its a much larger processor then A9, so unless they were able to save space elsewhere the die seems too small. IMO if they'd gone for an A15, we'd see a larger die and a huge amount of hype about the newer processor. Just bringing clock speed up to where Nvidia/Qualcomm/Samsung are makes more sense.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Possibly, but here's one other tidbit: in the past, Apple has moved to a new ARM architecture with each brand-new processor; i.e., the A4 was a Cortex A8 chip, A5 was Cortex A9, etc. To me, that also points to the A6 being a Cortex A15.

I think Apple will want to delay quad core CPUs as long as possible. I mean we all know how much desktop software isn't optimized for multicore. Mobile apps are even less so. A faster dual core will have more real-world benefit than adding more cores.

I think the single most important factor in perceived CPU speed on a phone is app startup time. And that part is almost never optimized for multiple cores. Multiple cores mostly benefit (heavy lifting) computation tasks and those rarely happen on phones. Servers usually take take of it. (The big exception is games. But even then the silicon is probably better invested in the GPU.)

The second most important factor is probably scrolling speed and general UI. Four cores don't help there, either. (In fact, much of it is limited to the main thread.)

I've been keeping fingers crossed that it's a quad-core CPU + quad-core GPU configuration clocked between 1.2 and 1.5GHz and with a minimum of 1GB RAM.

Apple definitely would have advertised the fact that it had quad cores if it actually did have quad cores. See: iPhone 4s announcement.

Right, my guess is the same as the author: two A-15 CPUs and two Series 6 GPUs. It sets the stage for two A-15s and four Series 6 GPUs for the next iPad. Maybe, someday, if there ever were a need they could go to four A-15s and fours series 6 GPUs. I have no idea why they would need that kind of horsepower though unless they were going to put into a 4K televsion.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Won't that use a lot more power?

Why? Especially if the OS downclocks it when not needed. Android devices from 1-2 years ago already had 1.5-1.6 GHz cpus. Add in the die shrink and that saves power and it is not like the iPhone 5 overall battery life is really that much better than the 4s.

There are a number of Android phones running dual A9s up at 1.5 GHz, and others that are running quad A9s near that. It doesn't seem unreasonable for Apple to just have two A9s running at 1.6 GHz to get doubled performance. Apple has never been that risky when it comes to silicon, so dropping a process node and a brand new completely untested in market architecture for their flagship iPhone sounds uncharacteristic.

That doesn't mean it won't happen. To me, the biggest indicator that it might actually be A15s is the A6 marketing name. Apple tends to be reserved when it comes to naming things, throwing an S or an X on things when they're more incremental like that.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz officially and even higher so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

My thoughts exactly. Furthermore, CPU performance is dependent upon way more than just the CPU itself. Decreases in memory latency by simply upping the memory frequency and tweaking the memory controller can lead to HUGE gains in performance in many benchmarks. It may very well be an A15, but I just don't get why people instantly jump to that conclusion as if it's obvious.

There are a number of Android phones running dual A9s up at 1.5 GHz, and others that are running quad A9s near that. It doesn't seem unreasonable for Apple to just have two A9s running at 1.6 GHz to get doubled performance. Apple has never been that risky when it comes to silicon, so dropping a process node and a brand new completely untested in market architecture for their flagship iPhone sounds uncharacteristic.

That doesn't mean it won't happen. To me, the biggest indicator that it might actually be A15s is the A6 marketing name. Apple tends to be reserved when it comes to naming things, throwing an S or an X on things when they're more incremental like that.

Except that the marketing name is exactly that: a marketing name. There is no law keeping them from calling a modified A5 an A6.

I would've bet that Apple would have been bragging about being the first to ship an A15.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Won't that use a lot more power?

Why? Especially if the OS downclocks it when not needed. Android devices from 1-2 years ago already had 1.5-1.6 GHz cpus. Add in the die shrink and that saves power and it is not like the iPhone 5 overall battery life is really that much better than the 4s.

Yeah, it's tough to rule out one or the other just yet. The only issue with higher clocks is the higher voltage needed to get there. Power scales proportionally to the square of the voltage so higher clocks are more power hungry than wasting die area on an improved architecture like the Cortex-A15.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Possibly, but here's one other tidbit: in the past, Apple has moved to a new ARM architecture with each brand-new processor; i.e., the A4 was a Cortex A8 chip, A5 was Cortex A9, etc. To me, that also points to the A6 being a Cortex A15.

Except that, if you stick with A5-generation naming, the naming options are VERY poor. A5 and A5x are taken. A5x2? A5s? Not to mention that any such name would lead to an even more underwhelming iPhone 5 launch.

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz officially and even higher so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

My thoughts exactly. Furthermore, CPU performance is dependent upon way more than just the CPU itself. Decreases in memory latency by simply upping the memory frequency and tweaking the memory controller can lead to HUGE gains in performance in many benchmarks. It may very well be an A15, but I just don't get why people instantly jump to that conclusion as if it's obvious.

There are a number of Android phones running dual A9s up at 1.5 GHz, and others that are running quad A9s near that. It doesn't seem unreasonable for Apple to just have two A9s running at 1.6 GHz to get doubled performance. Apple has never been that risky when it comes to silicon, so dropping a process node and a brand new completely untested in market architecture for their flagship iPhone sounds uncharacteristic.

That doesn't mean it won't happen. To me, the biggest indicator that it might actually be A15s is the A6 marketing name. Apple tends to be reserved when it comes to naming things, throwing an S or an X on things when they're more incremental like that.

Except that the marketing name is exactly that: a marketing name. There is no law keeping them from calling a modified A5 an A6.

I would've bet that Apple would have been bragging about being the first to ship an A15.

Apple doesn't usually talk about specific architectures when they're up on stage. The A5 switched to Cortex A9, but they didn't say that at the iPad 2 event: they instead said that it was "up to 2x faster" than A4 and had a "9x faster GPU". They said it was the "first dual-core tablet to ship in volume" but that was as technical as they got.

I'll do another article once we get a look at the chip, and I'll be the first to admit if I'm wrong. Gonna stick to my guns for now, though. :-)

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Possibly, but here's one other tidbit: in the past, Apple has moved to a new ARM architecture with each brand-new processor; i.e., the A4 was a Cortex A8 chip, A5 was Cortex A9, etc. To me, that also points to the A6 being a Cortex A15.

Except that, if you stick with A5-generation naming, the naming options are VERY poor. A5 and A5x are taken. A5x2? A5s? Not to mention that any such name would lead to an even more underwhelming iPhone 5 launch.

Keeping the A5 name would also make the iPhone 5 more of a 4ss (...stretch...).

Interesting analysis. One quibble, though. The RAM on these things is typically a separate die which is then combined with the CPU/GPU die during packaging, so the space required for 512 MB vs 1 GB shouldn't enter into the equation.

There are a number of Android phones running dual A9s up at 1.5 GHz, and others that are running quad A9s near that. It doesn't seem unreasonable for Apple to just have two A9s running at 1.6 GHz to get doubled performance. Apple has never been that risky when it comes to silicon, so dropping a process node and a brand new completely untested in market architecture for their flagship iPhone sounds uncharacteristic.

That doesn't mean it won't happen. To me, the biggest indicator that it might actually be A15s is the A6 marketing name. Apple tends to be reserved when it comes to naming things, throwing an S or an X on things when they're more incremental like that.

Except that the marketing name is exactly that: a marketing name. There is no law keeping them from calling a modified A5 an A6.

I would've bet that Apple would have been bragging about being the first to ship an A15.

Apple doesn't usually talk about specific architectures when they're up on stage. The A5 switched to Cortex A9, but they didn't say that at the iPad 2 event: they instead said that it was "up to 2x faster" than A4 and had a "9x faster GPU". They said it was the "first dual-core tablet to ship in volume" but that was as technical as they got.

I'll do another article once we get a look at the chip, and I'll be the first to admit if I'm wrong. Gonna stick to my guns for now, though. :-)

"first dual-core tablet to ship in volume" yes they didn't miss this opportunity."first phone to ship in volume with next gen ARM processor" didn't happen at the event.

"first phone to ship in volume with next gen ARM processor" didn't happen at the event.

ARM processors are much more obscure than dual core computers are.

And StackOverflow makes it pretty clear that it is a next-gen chip.

FearLES wrote:

Eraserhead wrote:

FearLES wrote:

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Won't that use a lot more power?

Why? Especially if the OS downclocks it when not needed. Android devices from 1-2 years ago already had 1.5-1.6 GHz cpus. Add in the die shrink and that saves power and it is not like the iPhone 5 overall battery life is really that much better than the 4s.

There's also another reason to go with a faster dual-core CPU than a slower quad-core design: iOS and its apps have been running on the dual-core A5 for some time and as such are already optimized for two cores, and adding another two cores would only unlock those performance gains for developers who put in the extra work.

Minor nitpick, but that's not generally the case with iOS. If you're doing a multithreaded app, chances are you're using Apple's Grand Central Dispatch, and once you're using that, you don't know (or care) how many actual cores are involved; the OS deals with it.

"first phone to ship in volume with next gen ARM processor" didn't happen at the event.

ARM processors are much more obscure than dual core computers are.

And StackOverflow makes it pretty clear that it is a next-gen chip.

FearLES wrote:

Eraserhead wrote:

FearLES wrote:

The A5 iphone is clocked at 800Mhz and many A9 series chips can run at 1.5 Ghz so why does this have to be an A15? The more likely answer is a die shunken A5 running at twice the clock rate 1.6GHz MAX for full horse power and slower when not needed to save the battery. Finally we need a better marketing name for this: A6

Won't that use a lot more power?

Why? Especially if the OS downclocks it when not needed. Android devices from 1-2 years ago already had 1.5-1.6 GHz cpus. Add in the die shrink and that saves power and it is not like the iPhone 5 overall battery life is really that much better than the 4s.

Fair point.

StackOverlow doesn't know. No documentation about what Armv7s is supposed to be is available.

Probably just some custom differences between the default architecture and the A6 one.

There os must one thing that makes me believe this is not a15 with gen6 gpu: yields. New architecture on new node size usually means low yields. And Apple don't do products with low yields as a failure to deliver quantity would be very bad for their image.

Andrew Cunningham / Andrew has a B.A. in Classics from Kenyon College and has over five years of experience in IT. His work has appeared on Charge Shot!!! and AnandTech, and he records a weekly book podcast called Overdue.